In a variety of physiological applications, particularly dentistry, appliances are provided as fixed detachable components on the human body, usually mounted by means of one or more implants which are attached to a bony substrate. For dental applications, these appliances are typically in the form of fixed artificial teeth, bridges, dentures and the like which are preferably detachable or removable. However, it is to be understood that such appliances may be constructed with a variety of configurations including telescopic units and misalignment appliances for use with misangled teeth for example as well as overlay dentures including bars attached to artificial teeth or a combination of artificial and natural teeth.
Variations in appliances as summarized above are well known to those skilled in the art and, accordingly, no further discussion of all of the various configurations is believed necessary. In any event, it is to be understood that the features of the present invention apply to all such variations of such appliances.
More broadly, such appliances may also take a variety of forms, referred to herein by the term "physiological", such as other physical features of the human body, particularly in connection with maxiofacial restoration where eyes, ears, noses, cheeks, etc. are removably attached to underlying bony substrates or structures.
In attaching such appliances to the underlying substrate, an implant is first mounted within the substrate. For example, the implant may be threaded into place in the substrate or secured therein by press-fit engagement or simple placement or a combination of the above.
Once the implant is secured in place within the substrate, it provides a mounting platform for a variety of appliances as summarized above. Generally, the appliance includes an abutment device suitable for attachment to the implant for example by threaded engagement, press-fit engagement, cementing or a combination thereof.
In typical processes, particularly for dental applications, a plastic component is commonly employed initially to form a mold cavity prior to casting of the actual appliance. Such processes are well known to those skilled in the art and are not described in further detail herein. In any event, where the component is made from plastic, elastomer or other material and used to form a tooth or teeth, the component is then commonly "burned out" and replaced by a metal frame forming part of the actual or finished appliance during the casting process.
Accordingly, the term "appliance" is employed herein to refer both to finished appliances as well as to initial devices such as the plastic component described above for use in casting of the finished appliance. As is also well known to those skilled in the art, the plastic component may also be termed a waxing sleeve, sleeve, coping, cylinder, etc.
In securing the applicant to the implant, directly or indirectly, it is necessary to resist substantial forces acting in a variety of directions including axially and laterally as well as angularly or in rotation. Accordingly, it has been found necessary in the past to stabilize the mounting of the appliance (directly or indirectly) upon the implant against one or more of these types of forces.
Generally, for dentures and other similar appliances commonly provided with multiple anchor points or implants, it is most important to provide stability against axial and lateral forces. For artificial teeth and the like including a single anchor point or implant, it is particularly important to provide stability against angular or rotational forces acting upon the appliance.
Generally, the prior art has employed cylindrically tapered indexing elements for securing dentures and the like to multiple implants. Such tapered indexing elements have been found to be particularly suitable for providing axial and lateral stability but, for the most part, have not been retrievable or aesthetically acceptable.
On the other hand, indexing elements with faceted surfaces have commonly been employed in artificial teeth and the like having a single anchor point or implant. In these applications, the faceted surfaces, typically a hexagonal configuration, have been found to be particularly suitable for providing angular or rotational stability.
The above discussion of particularly configured indexing elements is only representative of the prior art. However, it is particularly noted that the prior art has employed either tapered or faceted indexing elements. In addition, the prior art has employed faceted surfaces which are also tapered. See U.S. Pat. No. 4,016,651 issued Apr. 12, 1977 to Kawahara et al and U.S. Pat. No. 3,905,109 issued Sep. 16, 1975 to Cohen et al.
The use of such a variety of implants naturally led to a wide assortment of parts available for use by practitioners such as dentists. At the same time, such appliance mountings were sometimes limited in application by not being able to provide a desired combination of features such as axial and lateral stability, as well as angular or rotational stability in addition to patient comfort, esthetics and maintenance.